If you know about anyone using Monero for that purpose, you can't use Monero, since obfuscating the origin of transactions is something you do as a condition of participating in Monero (either as a miner or through paying transaction fees).
And if you have to go to north korea to cash out, then the convenience is much lower.
Having said that, if you are a crypto proponent, you would argue that cashing out to fiat will become less and less necessary as time goes on and simply swapping to USDT/USDC and spending that will become easier. The jury is still out on that one
You can (and people often do especially with banknotes) do crime and tax evasion with them, but you can't transport them across borders in large quantities easily.
Something like monero has the potential to be almost as fast and convenient as a fiat bank transfer but able to be done in any size and be untraceable - that's a combination that doesn't win you many friends in western governments
Everyone should just assume that if they're trying to hide themselves via some service, that said business will provide your information/data to the authorities, if asked to.